The present invention relates to a connection detecting circuit for detecting a state of connection between an electrically driven vehicle and a charger.
Conventionally, in electrically driven vehicles such as electric vehicles and plug-in hybrid vehicles, the vehicle is charged with power for driving by connecting a charger-side connector of a charger to a vehicle-side connector that is provided in a vehicle body.
If the charger-side connector is not connected to the vehicle-side connector correctly, charging may not be performed normally or the charger or the vehicle may be damaged due to coming-off of the charger-side connector. To avoid such an event, a technique is proposed in which a connection detecting circuit for detecting a state of connection between a vehicle-side connector and a charger-side connector is provided and a state of connection between the vehicle-side connector and the charger-side connector is determined using the connection detecting circuit.
In connection with such connection detecting circuits, techniques for detecting an occurrence of a circuit failure (high-side shorting, ground shorting, or the like) together with a state of connection to a charger are known. For example, the following Patent document 1 discloses a vehicular power shutting-off circuit that is equipped with an electric component provided in a vehicle, a housing unit that houses the electric component, and a stopping unit for stopping supply of power to a power line that is provided in the housing unit and connected to the electric component if it is determined that contact, from outside the housing unit, to the electric component and the power line has become possible. The power shutting-off circuit is further equipped with a connector that has a reception unit provided in the housing unit and a detachable unit capable of being attached to and detached from the reception unit and enables opening of the housing unit by detaching the detachable unit from the reception unit, a signal line that is connected when the detachable unit is fit into the reception unit and disconnected when the detachable unit is detached from the reception unit, and a voltage applying unit that applies a pulse-wave voltage having a fixed cycle to the signal line.
The stopping unit stops supply of power to the power line if determining that the high-level duration of a signal on the signal line has become longer than a preset time that is longer than a high-level duration, in each cycle, of the pulse waveform or the low-level duration of a signal on the signal line has become longer than a preset time that is longer than a low-level duration, in each cycle, of the pulse waveform.
[Patent document 1] JP-A-2013-116030